At the risk of coming across like a fool, wouldn't it make more sense to wait until we've got our players back and fit and played a couple games more to overcome the lack of preseason before we decide that everything about the team is shit?
It's a myth that our defensive stability was mostly down to Fernandinho, not that he was the best DM around. You are conflating two different things.
If last season we had both Kompany and Laporte in the form they showed in 2019, we would have been a completely different team. Posts like yours underestimate the CB crisis we had and overestimate the defensive protection Fernandinho provided. It will become clear already this season once Dias and Laporte form a partnership (fingers crossed!). We can be solid in defence even without Fernandinho in midfield (which doesn't imply that he wasn't the best DM in the world August 2017/February 2019).
Unfortunately with discussion of Fernandinho and everyone else for that matter things take extremes. Either he's perfect or he's awful. Can't be anything in between. No levels. Flawless or useless. At the back end of 16/17 people were just starting to suggest Silva and De Bruyne might not have been up to it. How right they were!
As you've pointed out though, there's much more nuance to this. You're right pointing out about Fern/Gundogan in 2019, but what you can actually extend from this is the De Bruyne injuries that season. We won the league with 99 points ahead of THAT Liverpool side without our best player for most of the season.
What made that team so strong was the lack of need for one player. Admittedly Bernardo stepped up big time that season, but the point is that everyone was working so hard and was so 'on it' that the team carried its players, not the other way around. Every player in that team had somebody who could step in and not ruin the quality of the side. The only possible exceptions were Ederson and Silva, the latter of whom I do believe has caused us an issue with his departure (more so than anyone else has or could).
Pep spoke about belief as of late, and it's concerning to hear but I believe it. We're timid. We don't press as well as often. Our defenders are perpetually uncertain of themselves, when they all have so much to offer. I think what's happened during last season has crushed these players a bit mentally. Although it's not impossible to recover from things like that, thankfully. It was belief that forced us over the line in 18/19 and in 17/18 belief was often spoke about with how we ground out winners by playing the same way and not abandoning ourselves.
You stick Rodri in that 17-19 side instead of Fernandinho and things probably won't be much different. We might have been a bit better, maybe a bit worse (which in 18/19 admittedly could have been costly). But not much different. If you stick 16-17 Touré in there, the same. It doesn't mean Fernandinho wasn't super high quality, it just means he wasn't single-handedly holding the side together. We had the much maligned Mahrez ahead of Sané in 18/19 and it worked. We probably could have stuck Jesus ahead of Aguero and in those years we would have been fine (to be clear not saying we should have, Aguero worked excellently enough).
On that note, you stick Fabinho in our 19/20 team instead of Rodri, he'll have the same problems. At Liverpool all he has are runners, it's a different story at City. Fernandinho too, as much as people wouldn't believe it.
The big positive is that first half v Wolves. Fitness wasn't an issue, we had verve and belief and importantly, we had a front three of Jesus, Foden, and Sterling, and we had Stones and Aké at the back. The front 3 pressed like hounds. Stones and Aké are both really good at stepping up and nullifying attacks early on the halfway line with press. All that meant was we could physically bully them, particularly thanks to Rodri, Fernandinho, Walker, and even Mendy. Even though we suffer majorly through a lack of control high up without Silva, Jesus and Foden are excellent at linking up play and bringing De Bruyne into the game in dangerous areas.
If after the international break when we've got close to a clean slate of health, our players are fitter, and Torres is more settled, we're still conceded 5 every game, then yeah a discussion about the apocalypse might be necessary. But until then I think people should chill on downplaying absolutely everything to the most negative extremes, particularly about recruitment which as you said wasn't a problem when we were winning.
Much like 16/17 going into 17/18 (with mostly the same players), it just takes a spark.